The following is a summary of “Distribution and Detectability of EGFR Exon 20 Insertion Variants in NSCLC,” published in the June 2023 issue of Thoracic Oncology by Ignatius et al.

About 5% to 10% of all EGFR mutations in NSCLC are EGFR exon 20 insertions (ex20ins). Due to the limited coverage of polymerase chain reaction (PCR) assays and the relatively recent use of next-generation sequencing (NGS), identifying patients with EGFR ex20ins is difficult. This study examines the spectrum of EGFR ex20ins variants in a large patient population from a global clinical trial and several real-world cohorts and the sensitivity of PCR reagents to detect these variants. 

Researchers performed this retrospective analysis on patients with NSCLC who underwent NGS or other sequencing testing and were known to have an EGFR ex20ins mutation. Patients were collected from a clinical trial (NCT02716116), a German chart review study, and the LC-SCRUM-Japan, GENIE, and U.S. COTA databases. The proportion of patients with ex20ins variants detectable by six commercially available and extensively used PCR kits was calculated in each data set. 636 patients with NSCLC who possessed EGFR ex20ins mutations were included in this analysis, and 104 distinct EGFR ex20ins variants were identified across all data sources. 

The percentage of patients whose ex20ins could have been detected by any PCR test alone ranged from 11.8% to 58.9%, depending on the data source. Their findings imply that the evaluated PCR tests would have missed over 40% of NSCLC patients with EGFR ex20ins mutations. NGS-based genetic testing is preferable to standard PCR assays and can significantly enhance the identification of EGFR ex20ins variants in NSCLC.

Source: sciencedirect.com/science/article/pii/S1556086423000953